How to wait for a process to complete using tcl-expect

Question

I am writing a script using expect in which I have to rlogin to some host & after that I need to send some commands. Now I want to exit to that host and relogin again to some other host and send some commands. But the run of my script is not waiting for first host to complete its jobs and exit instead it sends other commands in between the previous process. How can I achieve this using expect please guide?

Sample code is as follow :

#!/usr/local/bin/expect -f

spawn rlogin host1
expect "%"
send "source xyz.csh\r"
send "exit\r"
expect "%"

spawn rlogin host2
some set of commands

Answer 1

Can you elaborate on "still script sending rest of the commands in between the previous process. "

I tried this and it worked.

spawn ssh host1
expect ":"
send pwd1
expect "%"
send "echo hi\r"
expect "%"
send "exit\r"
expect eof
spawn ssh host2    
expect ":"
send pwd2

Answer 2

you're forgetting to "hit enter". After sending exit, the way to wait for the process to end os expect eof:

send "source xyz.csh\r"
expect "%"
send "exit\r"
expect eof

Answer 3

I found this post after I ran into a race condition problem: sometimes the script completed as expected and other times it didn't. Adding a catch statement to the script ensured the desired outcome every time:

[...]
expect eof
catch wait result

Answer 4

Try this construct when command is time consuming:

. . .
send "command\r"

expect {
    timeout {
        puts "Running..."
        exp_continue
    }
    "%PROMPT%" {
        puts "Finished."
    }
}

send "next command\r"
. . .

On timeout you will be continuosly waiting with exp_continue command for %PROMPT%.